Rule of thumb, if its used anywhere a laptop is usually used then the setting i.e. work/school/lounge areas/waiting rooms etc is appropriate for such a device.
Places where your attention should be focused elsewhere i.e.
-Gym
-family resturant table
-super market etc
Looks silly, oh and pic taking and video recording looks reeeeaaallly jerkish like...
I have to disagree. Why not use it where YOU feel it helps the most? There are not rules, seriously...
Gym - Okay the ipad is a bit big, but something like the mini or Nexus 7, heck yeah. First, with a BT headset you have your tunes. Second, I like to track my sets, reps and weight each workout; plus I have set routines for certain days. I like to go back a few days and see what I lifted, my progression, etc as I workout as well. I used to do this with pen and paper in a little notebook. Now I can not only listen to my music, but also track and refer back to my previous workouts real time. Sometimes I want to substitute one exercise for another, I can easily check this and then form/motion right there, while at the gym. Then while doing cardo, boom, Hulu, Netflix, read a book, whatever to pass the time. Doing this on the iPhone is a HUGE PITA, too small a screen, too small a keyboard.
Restaurant - On vacation, stopping for something to eat, want to plan with the family where to go next, reserve tickets, check open/close times, find attractions, seems logical and useful to me. I take lots of motorcycle trips to new places, its nice to sit and eat and look at maps to find interesting roads, confirm routes, see what is near by...oh wait, someone is looking, lets go in the bathroom instead?? Really? Who cares what people assume and think...
Supermarket - Got a big family with a long list to buy? Shop once a month? Need special items? Forgetful? If you are going to carry it anyway, WHY NOT USE IT? Not just for lists, but online coupons, instant comparison shopping and more...sure an iPhone will work, but again, the larger screen is so much better and easier.
I say, use the thing where it proves useful to you. People worry too much about fitting in and what others think. Chances are, no one is thinking anything, and if they do, who really cares?